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Re: Vertical Trajectory System (with some 3D printed parts)

Posted: Mon Jul 16, 2018 9:17 am
by SpaceManMat
Can’t wait. Nice bit of science btw.

Final Preparations for Flight

Posted: Mon Jul 30, 2018 6:35 pm
by OverTheTop
Final Preparations for Flight
Getting ready to light a fire under this next weekend. Exciting times ahead. I have done final assembly and testing on the VTS assembly and it is behaving as I expect. Velociraptor R has been prepped and is ready for final stacking and inserting the K1103X motor. Batteries are charging for flight as we speak :) .

Here she is before I fitted the airframe over everything:
FoamPacked.JPG

Notice that a lot of the interstices have been packed with foam to assist this, what is essentially a breadboard, assembly in not having anything rattle around under acceleration.

One of the last items on the list is a breakwire for shutting the VTS off when the assembly breaks from the rocket at apogee. That will save my batteries and servos, keeping them good for next flights. So I want a fine wire I can cut easily, but it needs to be robust so it doesn't prematurely neutralise the VTS. Here is what I have come up with:
Breakwire.JPG

I have taken a washer and applied a countersink tool to each side. This leaves a nice sharp edge in the middle of the donut to cut the wire when there is a pull on the harness. The washer will be held with a cable tie to the recovery harness.

A nice new set of fins should be printed in Pro Grey tomorrow, for fitting onto the assembly later in the week.

Now, onto a camera band with four cameras for the flight...

Flight Fins Finished

Posted: Thu Aug 02, 2018 6:38 pm
by OverTheTop
Flight Fins Finished
Since the strength testing showed the strongest parts were printed on the SLA printer in Pro Grey, a complete set was printed. Two of the fins have slightly more travel than the other pair. I didn’t want the roll control fins to not have enough authority, so I gave them an extra 3 degrees of swing each way, which is controlled by mechanical stops on the rear of the flange. The main fins on the Velociraptor R are a little warped since it sat in the field for 11 months in a previous life. Only two of the four fins contribute to roll maneuvering with this setup and I wanted to make sure they were not hamstrung too much. Note the great surface finish on the SLA printed parts.

What you see there is straight out of the printer without any further finishing.
finsresize.jpg


Here she is all buttoned up.
allresize.jpg


As usual, click images for a better view :)

Launch has been cancelled for this weekend :( due to weather unfortunately. Maybe it will fly the following week, weather permitting.

Re: Vertical Trajectory System (with some 3D printed parts)

Posted: Fri Aug 03, 2018 10:58 am
by air.command
The fins look great OTT! Good luck with the flight, I'm very much looking forward to the flight report. How do you think the fins will go on landing?

Re: Vertical Trajectory System (with some 3D printed parts)

Posted: Fri Aug 03, 2018 12:17 pm
by OverTheTop
Fins should be fine. NC assembly lands after the main airframe so velocity under the chute should be less than the average sink rate.

Fins are strong. They will be fine. Servo flange, maybe...

Re: Vertical Trajectory System (with some 3D printed parts)

Posted: Fri Aug 03, 2018 3:21 pm
by SpaceManMat
Awe man, looks superb.

Re: Vertical Trajectory System (with some 3D printed parts)

Posted: Sun Aug 12, 2018 10:42 am
by OverTheTop
Still On Hold
:(

All buttoned up and ready to go. Just need the weather to cooperate. Launched cancelled for a second time. Trying again for 19th August.

OnWallOnHold.jpg

VTS is GO for launch!

Posted: Fri Aug 24, 2018 1:45 pm
by OverTheTop
VTS is GO for launch!

Just had confirmation that we are go to launch on 26th August. Yee Ha!

Re: VTS is GO for launch!

Posted: Fri Aug 24, 2018 5:39 pm
by SpaceManMat
OverTheTop wrote:VTS is GO for launch!

Just had confirmation that we are go to launch on 26th August. Yee Ha!


Cool, can’t wait to see how it goes.

Re: Vertical Trajectory System (with some 3D printed parts)

Posted: Mon Aug 27, 2018 12:43 pm
by drew
How'd you go OTT?!? Fingers crossed.

Re: Vertical Trajectory System (with some 3D printed parts)

Posted: Mon Aug 27, 2018 1:07 pm
by OverTheTop
Flight was entirely nominal for a HPR flight. Landed fine, no damage to anything.

Probably not enough control authority, particularly with a light motor in the tail giving me about 2.8cal of static stability.

Will download data, video, and analyse. Should be able to post results in the next week if I am lucky.

You will be the second to know the results :wink:

Re: Vertical Trajectory System (with some 3D printed parts)

Posted: Mon Aug 27, 2018 2:06 pm
by drew
That's great news d00d! Given it was your first flight of the system I was slightly concerned things might go a bit sub-optimal. Glad to hear that your flight was nominal and you've got data! That's the most important thing. :D

Re: Vertical Trajectory System (with some 3D printed parts)

Posted: Tue Sep 04, 2018 2:12 pm
by OverTheTop
Quick Update
Life is getting in the way of this currently :( . I still have not had anything like a good look at the logging and meaningful analysis.

Basic synopsis:
:arrow: Flight was nominal, like any standard HPR flight. It was a bit of a big gravity turn by the looks of it, but no worse than other flights on the day. All hardware recovered well and there was not damage.
:arrow: Quick inspection of the servo logging showed it was working, at least in the roll axis. There was either some Dutch roll happening or roll-axis oscillation. Not sure which yet.
:arrow: The three keychain cameras suffered bad batteries, so no visuals on the fins :(. One side-looking camera recorded well. New cameras ordered for next time. I may connect an external battery to run them.
:arrow: I am in the process of digging into this. First step was to replace the two flight batteries in the VTS that were drained when a RBF pin fell out when I unloaded the VTS from the car to the bench. Managed to get to that last night, and then the LiPo for the TeleMega died...


As I said, no detail findings yet. I will let you know when I know. Stay tuned!

PadResize.jpg

Re: Vertical Trajectory System (with some 3D printed parts)

Posted: Tue Sep 04, 2018 7:57 pm
by SpaceManMat
OverTheTop wrote:Quick Update
Life is getting in the way of this currently :( . I still have not had anything like a good look at the logging and meaningful analysis.

Basic synopsis:
:arrow: Flight was nominal, like any standard HPR flight. It was a bit of a big gravity turn by the looks of it, but no worse than other flights on the day. All hardware recovered well and there was not damage.
:arrow: Quick inspection of the servo logging showed it was working, at least in the roll axis. There was either some Dutch roll happening or roll-axis oscillation. Not sure which yet.
:arrow: The three keychain cameras suffered bad batteries, so no visuals on the fins :(. One side-looking camera recorded well. New cameras ordered for next time. I may connect an external battery to run them.
:arrow: I am in the process of digging into this. First step was to replace the two flight batteries in the VTS that were drained when a RBF pin fell out when I unloaded the VTS from the car to the bench. Managed to get to that last night, and then the LiPo for the TeleMega died...


As I said, no detail findings yet. I will let you know when I know. Stay tuned!

PadResize.jpg


Well that’s a bit anoying but I guess you leart a few things. I did initially add a tie around my remove before flight pins so they could not fall out. I since dropped that idea as uneccissary, but for more complex flights like this you might want to consider it.

Re: Vertical Trajectory System (with some 3D printed parts)

Posted: Wed Sep 05, 2018 7:36 am
by OverTheTop
Well that’s a bit anoying but I guess you leart a few things. I did initially add a tie around my remove before flight pins so they could not fall out. I since dropped that idea as uneccissary, but for more complex flights like this you might want to consider it.


The pins are visible in the above pic held in place by tape or elastic bands. Sometimes after a launch they get treated a little less carefully than before. First time this has happened.